Termination control for a condensing clothes dryer



Nov. 23, 1965 M. A. MENK ETAL 3,218,730

TERMINATION CONTROL FOR A CONDENSING CLOTHES DRYER Filed June 14, 1962 4Sheets-Sheet 1 r INVENTORS m N Melvin A. Menk BY James L. Miller TheirAttorney Nov. 23, 1965 A. MENK ETAL 3,218,730

TERMINATION CONTROL FOR A CONDENSING CLOTHES DRYER Filed June 14, 1962 4Sheets-Sheet 2 INVENTORS. Melvin A. Menk Y James L. Miller Nov. 23, 1965M. A. MENK ETAL 3,218,730

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Melvin A. Menk James L. Miller Tlll'lllll ||ll |l||| BY 50 I00 I50 200250 300 Tem era/ure "F p Their Attorney United States Patent Office3,218,730 Patented Nov. 23, 1965 3,218,730 TERMINATION CONTROL FOR ACONDENSING CLOTHES DRYER Melvin A. Menk and James L. Miller, Dayton,Ohio,

assignors to General Motors Corporation, Detroit,

Mich., a corporation of Delaware Filed June 14, 1962, Ser. No. 202,48612 Claims. (CI. 3445) This invention relates to a domestic appliance andmore particularly to an improved control arrangement for terminating aclothes drying cycle.

The clothes drying art has been faced with the disadvantage of ventingthe moisture laden exhaust products from a dryer to the outsideatmosphere. For those situations where construction or other problemsprevent outside venting, a condensing clothes dryer has been provided ofthe type taught generally in the patent to Whyte et al. 3,032,887,issued May 8, 1962. The condensing dryer includes a recirculating dryingair flow system for picking up moisture from the clothes and acondensing means such as a cooling air fiow system which blows incounterflow heat transfer relationship to the recirculating air. Thus,the recirculating air picks up moisture in the tumbling drum and, whilepassing through the condenser, is cooled by the cooling air flow systemto release the entrained moisture as condensate.

Various controls have been used with condensing dryers to automaticallyterminate the drying cycle and it is to an improved control for thisresult that this invention is directed.

Accordingly, it is an object of this invention to terminate the dryingcycle of a condensing dryer automatically.

Another object of this invention is the provision of a control for acondensing dryer which uses the temperature of the heated inlet air toterminate the drying cycle.

A more specific object of this invention is the provision of a controlwhich includes a drying cycle termination thermostat in the heaterchamber ahead of the tumbling drum to operate a timer motor, a dryingtemperature control thermostat in the exhaust air from the tumbling drumhaving an ON position for energizing the heater and an OFF position inseries with said drying cycle termination thermostat, said drying cycletermination thermostat acting to terminate the drying cycle bycontinuously operating the timer motor when the heater is deenergizedand the temperature of the air in the heater chamber falls below apredetermined value.

Another object of this invention is the provision of a drying cycletermination control having a preset temperature for terminating thedrying cycle of regular fabrics at one temperature, a cycling controlfor regulating the temperature during drying and means 'for relatingsaid termination control to said cycling control for terminating thedrying cycle of delicate fabrics at a temperature different from saidpreset temperature.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

FIGURE 1 is a fragmentary perspective view of a condensing dryer withparts broken away to show a recirculating air flow system and a coolingair flow system suitable for use with this invention;

FIGURE 2 is a schematic representation of the condensing dryer detailedin FIGURE 1;

FIGURE 3 is a schematic wiring diagram of the inlet air temperaturetermination control of this invention;

FIGURE 4 is a timer cycle chart showing the positions of the timerswitches in FIGURE 3;

FIGURE 5 is a graphic representation of a REGULAR load of clothes(cottons, linens, etc.) being automatically dried in accordance with theteachings of this invention;

FIGURE 6 is a graphic representation similar to FIG- URE 5 for a sixpound DELICATE load of clothes (man made fabrics such as nylon, Acrilon,etc.); and

FIGURE 7 is a graphic representation for a two pound DELICATE load.

In accordance with this invention and with reference to FIGURE 1, acondensing type clothes dryer 10 is illustrated. The clothes dryer 10 iscomprised of an enclosing casing on the top of which is a controlhousing 18. The housing 18 supports a control knob 14 which may beselectively positioned for initiating and controlling the drying cyclein accordance with the teachings of this invention and a knob 16 forsetting the type of fabric to be dried and thus the temperature to bemaintained during the drying cycle. A tumbling drum 20 is disposedwithin the casing and interposed between a front bulkhead 22 and a rearbulkhead 24. The tumbling drum 20 is comprised of a perforated rear wall26 which is rotatably supported on a stub shaft 28 journalled on therear bulkhead 24. Further, the tumbling drum 20 includes a cylindricalaccess collar 32 which is relatively rotatably supported by a front portblade 34 carried on the front bulkhead 22. The access opening formed bythe collar 32 is closed by a door shown at 36. On the door is a lintcollecting housing 38 which projects into the access opening collar 32of the tumbling drum when the door is closed, an annular seal 37engaging the port plate to force all air leaving the tumbling drum totravel through the lint collecting housing.

The recirculating air flow system is defined by perforations 40 in thefront port plate 34 which open into a front duct 42. This front ductopens into an inlet header 46 for a heat exchanger or condenser, showngenerally at 48. The condenser 48 is comprised of a plurality ofslightly leftwardly sloping tubes 50 which interconnect the inlet header46 with an outlet header 52. A recirculating air blower 54 has its inlet56 connected to the outlet of the outlet header 52 and impels airthrough a flexible conduit 58 to a rear duct 60 behind the rear bulkhead24. The rear duct has an opening 62 through the rear bulkhead 24 into anannular chamber formed by a generally channel-shaped annular pan 64fastened to the front side of the bulkhead 24. The annular channel orheater housing provides the means for enclosing and supporting theannular heating elements 66 in juxtaposition to the perforated rear wall26 of the tumbling drum.

Thus, recirculating drying air is impelled by the blower 54 through theflexible conduit 58 to the rear duct 60. From the outlet opening 62 inthe rear duct 60, air enters the heater chamber formed by the channelpan 64. The air is heated by the heating element 66 and enters thetumbling drum 20 through the perforations in the drum wall 26. Moistureis entrained from the clothes in the tumbling drum and this moistureladen air flows out of the drum by way of the access opening collar 32and the lint collecting housing 38 into the front duct 42 by way of theport plate openings 40. This air is channeled through the inlet header46 for the condenser 48 and through the tubes 50 into the outlet header52. While traveling through the condenser tubes, moisture is depositedtherein by the cooling air fiow system which will be described nextfollowing and this moisture flows by gravity into the outlet headerwhere an opening 70 channels the moisture to a mating opening 72 and aremovable substantially enclosed envelope-like condensate container 74.

The cooling air system for the condenser 48 is comprised of a coolingair blower 76 connected by way of a fan-shaped duct '78 to the rear sideof the condenser tubes 50. The blower 76 is effective to draw airthrough a screened opening 80 at the front of the condenser tubes, overthe outside of the condenser tubes and into the duct 78, from whichpoint the air is impelled to the atmosphere. This relatively cool airwill cool the condenser tubes 50 and cause condensation of moisture fromthe recirculating air therein.

A single prime mover or motor 82 is effective through a belt and pulleysystem (not shown) behind the rear bulkhead 24 to rotate the tumblingdrum 20 and to drive the cooling air blower 76 and the recirculating airblower 54.

The two air flow systems have been shown by arrows in FIGURE 1the solidarrows indicating the recirculating air flow and the dashed arrowsindicating the cooling air flow for the condenser 48.

Turning now to FIGURE 2, the inlet air temperature dryer terminationcontrol of this invention will be described-components in FIGURE 2carrying the same reference numeral as their counterparts in thedetailed version of FIGURE 1. The basic relationship of the condensingdryer components shows the tumbling drum 20 in a recirculating airstream initiated by the blower 54. Diposed in the recirculating airstream on opposite sides of the tumbling drum is the heater 66 and thecondenser 48 which may be either air cooled as shown in FIGURE 1 orwater cooled. The condenser removes the moisture from the recirculatingair stream which has been picked up from the clothes in the tumblingdrum 20 and also reduces the air temperature when the clothes are dryfrom about 170 F. at the inlet of the condenser to about 130 F. at thecondenser outlet. This pronounced temperature differential is used toadvantage in the automatic control of this invention as will beunderstood more fully hereinafter.

The schematic wiring diagram for controlling the automatic drying cycleof the condensing drying is illustrated to FIGURE 3. The control circuitincludes a power supply L L and a neutral line N. Disposed inintercepting relationship to the various dryer componets is a timerhaving its control knob 14 exposed on the console of the dryer andenclosing a plurality of cam actuated switches, such as 100 in theheater circuit, 102 in the timer motor circuit, 104 in the circuit forthe main motor 82 and 106 leading to an alarm 108 which may be soundedto signal the end of the automatic drying cycle. The various timerswitches 100, 102, 104 and 106 may be sequentially operated by a timershaft 110 incrementally advanced or rotated whenever a timer motor 112-is energized. Other components in the drying circuit may include a doorswitch 114 having a position in series with the main motor 82 when thedoor is closed and a position in series with a lamp 116 when the door isopened. In the heater circuit there are various safety features such asa high limit control 118 which opens if temperatures exceed a safe levelwithin the dryer and a centrifugal switch 120 which closes whenever theprime mover or motor 82 is satisfactorily in operation.

In addition to the foregoing, the novel automatic dryer control of thisinvention includes a fabric selector switch 122 which may be set throughknob 16 or push buttons for a REGULAR drying cycle or a DELICATE dryingcycle depending on the type fabric to be dried. More particularly, thecycle selector switch 122 includes a main heater switch 124 having afirst position contact 126 whenever any heat is required in the dryingcycle (knob 16 set for either REGULAR or DELICATE) and a second positioncontact 128 when NO HEAT is desired. The cycle selector also includes aswitch 130 having a firstv position contact 132 in series with a biasingheater 134 (knob 16set forDELICATE) and a second position 4 contact 136for by-passing the biasing heater 134 (knob 16 set for REGULAR).

The automatic control circuit includes an exhaust air thermostat orcycling control 140 which may be positioned on the door 36 in the pathof air leaving the tumbling drum through the lint collecting housing.This cycling control includes a temperature responsive switch 142 havinga first position contact 144 in series with the main heater 66 and asecond position or back contact 146 connected through an inlet airthermostat or termination control 148 to the timer motor 112. The switch142 is selectively heat biased in order to provide a low temperaturerange for DELICATE fabrics (142 F.- 150 F.) when the selector switch 130is engaged with contact 132 and a high temperature range for REGULARfabrics F.-177 F.) when the switch 130 is moved to contact 136. Assuminga REGULAR cycle, for instance, the switch 142 engages the contact 144when the temperature of air leaving the tumbling drum is belowapproximately 170 F. to energize heater 66. On the other hand, theswitch 142 engages the back contact 146 when the exhaust air temperatureexceeds approximately 177 F. Thus, the switch 142 moves between contacts144 and 146 to maintain a predetermined temperature within the tumblingdrum.

The inlet air thermostat or termination control switch 148 has an openposition so long as the temperature of the air entering the tumblingdrum is above 210. However, the switch 148 remains closed whenever theinlet air temperature is below 200 F. With the foregoing components, thecontrol cycle for a DELICATE or REGULAR drying cycle will be describednext following.

General On the Automatic drying cycle of this invention, the user setsthe timer knob 14 to either DELICATE or REGULAR and the Fabrics controlknob 16 for the type of material being dried. This indirectlyestablishes the drying time and temperature. The Automatic drying cycleis based on temperature and, on the DELICATE setting, the timer runsonly when the heater element is off and the cycle termination switch 148is closed or when timer switches 102 and 104 are closed.

Regular load drying cycle Referring to FIGURES 3, 4 and 5, a REGULARdrying cycle will be initiated when the cycle control knob 14 ismanipulated to position the contacts as shown at the REGULAR startindicator in FIGURE 4. At the same time, the operator will operate theselector switch 122 by manipulating the control knob 16 to position theswitch 124 on contact 126 and the switch 130 on contact 136 for theREGULAR fabric drying temperature. As the timer is advanced to theREGULAR start position, timer switches 100, 102 and 104 are closed.Thus, the main motor 82 is energized through timer switch 104 to startthe rotation of the tumbling drum 20 and the recirculation blower 54. Atthe star of a drying cycle, the temperature of the recirculating airwould be below the temperature setting of the selector switch 124 andthe temperature cycling control switch 142 will engage the contact 144to energize the heater 66. As aforesaid, the centrifugal switch 120 willbe closed when the main motor 82 is running. Note also that thetermination control switch 148 which is measuring drum inlet airtemperature is closed at the start of the cycle since the initialtemperatures of the recirculating air are below 200 F.

The timer motor. 112 will be energized from L through the timer switch104, jumper line 150, timer switch 102, the timer motor 112 to the otherside of the line N. As the automatic cycle advances, and with referenceto FIG- URE 5, the temperature at the exhaust air thermostat or cyclingcontrol switch 140 is shown by the curve portion 154 and thetemperatures occurring at the inlet air thermostat or terminationcontrol switch 148 are evidenced by the curved portion 156. Note thatthe temperatures at both the inlet and the exhaust are increasing aswould be expected with the heater 66 energized. At a point .158, thetermination control switch 148 opens to break the shunt or parallel paththrough the temperature selector switch 130 and the timer switch 104;and the timer motor 112 is then energized solely through the timerswitch 102. The temperature of the recirculating air at the outlet ofthe tumbling drum continues to increase to a point 160, at which point,the temperature of the air coming out of the tumbling drum exceeds 177so that the switch 142 moves to its position in engagement with the backcontact 146. This deenergizes the heater 66 and the recirculating airtemperature starts to cool along the curve portion 162 until a curve:point 164 is reached, at which point, the switch 142 again moves intoengagement with the contact 144 to reenergize the heater 66 along acurve portion 166. Thus, the heater 66 is energized and deenergizedwhile the REGULAR clothes load is being driedeach period of heaterenergization being progressively shorter as the clothing gives up itsmoisture and, thus, its latent load to the recirculating air stream.

Simultaneously with the cycling of the heater 66 and, more specifically,at a point 168 which coincides with the point 160 on the exhaust airtemperature curve, the temperatures of the recirculating air at theinlet of the tumbling drum start to cycle in response to the on-olfoperation of the heater 66. Thus, when the heater is 011 and the exhaustair is falling as at curve portion .162, so also does the airtemperature fall off at the inlet of the tumbling drum as evidenced bycurve portion 170. Since the heater is energized for progressivelyshorter periods (curve portion 166 spans a greater period of time thancurve portion 172), it would be natural to expect that the temperaturegradient of the inlet air adjacent the heater would fall off gradually.This is evidenced by the fact that inlet air temperature curve points174, 176 and 178 are progressively lower and are approaching the 200 F.point 180, at which time, the termination control switch 148 will close.

The foregoing explanation of FIGURE 5 shows the various temperaturevariations wihch occur at the cycling control 140 and the terminationcontrol 148 throughout the entire automatic drying cycle. It isnecessary now to return to FIGURE 4 to explain the interplay between thethermostatic controls 140 and 148 and the timer motor 112. It can beseen that the timer switches 100, 102 and 104 remain closed for a timedperiod 105 from start up until the timer switch 102 opens to initiate anindefinite pause period 182. This timed period 105 of approximatelyeight minutes built into the timer is shown by upwardly leftwardlydiagonal shading in FIGURE 5. Once timer switch 102 opens at the end ofthis timed period, the energization of the timer motor 112 is under thesole control of the series arranged termination control 143 and thetimer motor switch 104 through the fabric selector switch 130 engaged oncontact 136. In other words during the REGULAR drying cycle, the cyclingcontrol switch 142 on its back contact 146 does no more than parallelthe circuit to the termination control 148. Thus, from the inlet aircurve point 159 to the curve point 180 the termination control 148remains open and the timer motor 112 deenergized. As soon as the curvepoint 180 is reached, the termination control switch 148 closes and thetimer motor 112 will be reenergized to advance the automatic cyclethrough the pause period 182. At its first timer pulse afterreenergization, the timer motor cam shaft 110 will open the timer switch100 to deenergize the heater circuit while maintaining closed the timerswitch 104 to continue the recirculating air in a COOL-OFF period tolower the temperature of the fabric to a point suitable for handling.The timer motor switch 102 will be closed for the duration of thecool-oft period. The REGULAR drying cycle will be terminated at theconclusion of the cool-off period when the timer switch 106 is closed toenergize the alarm 108 after which timer switches 102, 104 and 106 willbe opened to terminate the drying cycle.

Delicate load drying cycle Using FIGURES 3, 4 and 6 for the operationaltimer sequence of the condensing dryer, assume that a DELI- CAT Esetting on the Timer and on the Fabrics control has been made. Theswitches 104 and of the timer are closed but switch 102 for the timermotor is open. Referring back to FIGURE 3, note that the circuit from Lthrough the timer switch 100, the fabrics control switch 126, cyclingcontrol switch 142, limiter control 118, heater element 66 andcentrifugal motor switch to L is complete when the motor comes up tospeed. In normal operation on DELICATE, current is supplied from timerswitch 104 through the internal circuit switch of the Fabrics control tothe heater or resist-or 134 in the cycling control to cause the controlswitch 142 to open sooner than its normal air operating temperature.Note: The resistor 134 is not energized on the high temperature orREGULAR fabric settings and the cycling control regulates the dryer asthough it were a normal 177 F. thermostat.

When the clothes load gets up to heat, approximately F. air temperature,bimetal disc switch 142 closes on its back contact 146-approximately 177F. i5 disc temperature at rated 240 volts clue to the additional heatbeing supplied by the resistor 134. Current then flows through to thetermination control and, if the switch 148 is closed, current issupplied to the timer motor to advance the timer. Due to the long heatperiod of the first cycle the termination control switch 148 will morethan likely remain open during the entire heater element OFF period 192of the first cycle (FIGURE 6) and the timer will not advance. During thesecond heater element ON period 194, less heat is required to bring theload up to heat. This allows the terminating control area at the rear ofthe tumbling drum to cool more rapidly so that switch 148 can close toadvance the timer during the second element OFF period 1%. Note: Timeradvance is shown by two differently shaded areas in FIG- URES 6 and 7;one type of shading indicates pause periods of indefinite duration whilethe timer is under the combined control of the termination controlswitch 148 and the cycling control switch 142; another type of shadingindicates programmed or timed periods when the timer motor is energizedcontinuously through the timer switch 102.

As the DELICATE clothes load dries and progressively less heat isrequired to bring the dryer up to temperature, the terminating controlarea remains cooler and the timer will advance for longer periods, i.e.,shaded area 198 is longer than shaded area 200. Once the timer advancesthrough the pause period 186, using up the last of the four minuteinterval built into the timer pause period as at 201, the timer switch102 is closed to drive the timer motor continuously for approximately 12minutes and the heater element cycles OFF and ON as required during thistimed period 202. At the end of the timed period, the timer switch 102open again and current must again be supplied through switch 142 andcontact 146 of the heat control and through the termination control 148to drive the timer approximately one minute. In FIGURE 6 this second oneminute pause period is made up of shaded sections 204 and 206. When thesecond pause period 182 is used up, timer switch 102 then closes todrive the timer through approximately a 7 minute cool-off period. Heaterelement switch 100 in the timer is open during this cool-off period.

FIGURE 7 is a graphic representation showing the rying cyclecharacteristics for a two pound DELICATE load. The foregoing explanationfor the six pound DELICATE load should provide adequate background for acomplete understanding of FIGURE 7.

It should now be seen that an improved automatic con trol has beenprovided for a condenser dryer. Throughout the time that air is beingrecirculated to dry the clothes, a condenser is effective to remove themoisture from the air and to cool the recirculating air as it gives upits heat of condensation. The pronounced cooling effect afforded by acondenser in the recirculating air stream when the clothes load is dryand the progressively decreasing heating effect of the heater throughoutthe drying cycle combine to effect an improved termination control whichvery accurately senses the proper end point dryness of the clothes load.Further, a circuit arrangement has been taught which will permit asingle termination control to terminate drying cycles for differentloads at difierent temperatures.

While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows.

1. In combination with a condensing clothes dryer having means defininga recirculating air stream, means for condensing moisture from saidrecirculating air stream, means for tumbling clothes in saidrecirculating air stream, heating means on the upstream side of saidtumbling means for heating said recirculating air stream and blowermeans for initiating said air stream, a control circuit comprisingtiming means for sequentially controlling said heating means and saidblower means in a programmed drying cycle of predetermined durationincluding a timer motor to advance said drying cycle, first switch meansthermally responsive to the temperature of said recirculating air streamon said upstream side of said tumbling means and in series electricalflow relationship with said timer motor for energizing and deenergizingsaid timer motor, said first switch means having a closed position forenergizing said timer motor when the temperature of said recirculatingair stream at said first switch means is below a first predeterminedvalue and an open position for deenergizing said timer motor when thetemperature of said recirculating air stream is above said firstpredetermined value, second switch means thermally responsive to thetemperature of said recirculating air stream on the downstream side ofsaid tumbling means and manually selectively electrically connected to aportion of said timing means and in selective series electrical flowrelationship with said first switch means or said heating means, saidsecond switch means having a first position in series with said heatingmeans when the temperature of said recirculating air stream at saidsecond switch means is below a second predetermined value to heat saidrecirculating air to dry the clothes and a second position in serieswith said first switch means when the temperature of said recirculatingair stream at said second switch means is above said secondpredetermined value to condition said timer motor to advance said dryingcycle, said drying cycle being terminated in a time interval longer thansaid predetermined duration of said programmed drying cycle when saidfirst switch means remains in said closed position due to the action ofsaid condensing means and said second switch means moves to said secondposition to energize said timer motor until said portion of said timingmeans deenergizes said control circuit.

2. In combination with a condensing dryer having means defining arecirculating air stream, means for condensing moisture from saidrecirculating air stream, means for tumbling clothes in saidrecirculating air stream, and heating means on the upstream side of saidtumbling means for heating said recirculating air stream, a controlcircuit comprising timing means for sequentially controlling saidheating means in a programmed drying cycle of predeter mined durationincluding a timer motor to advance said drying cycle, first switch meansthermally responsive to the temperature of said recirculating air streamon said upstream side of said tumbling means and in series electricalflow relationship with said timer motor for energizing and deenergizingsaid timer motor, said first switch means having a closed position forenergizing said timer motor when the temperature of said recirculatingair stream at said first switch means is below a first predeterminedvalue and an open position for deenergizing said timer motor when thetemperature of said recirculating air stream is above said firstpredetermined value, second switch means thermally responsive to thetemperature of said recirculating air stream on the downstream side ofsaid tumbling means and electrically connected to a portion of saidtiming means and in alternating series electrical flow relationship withsaid first switch means or said heating means, said second switch meanshaving a first position in series with said heating means when thetemperature of said recirculating air stream at said second switch meansis below a second predetermined value to heat said recirculating air todry the clothes and a second position in series with said first switchmeans when the temperature of said recirculating air stream at saidsecond swtich means is above said second predetermined value tocondition said timer motor to advance said drying cycle, said dryingcycle being terminated in a time interval longer than said predeterminedduration of said programmed drying cycle when said first switch meansremains in said closed position due to the action of said condensingmeans and said second switch means moves to said second position toenergize said timer motor until said portion of said timing meansdeenergizes said control circuit.

3. The combination of claim 2 including manually selectable meansinterposed between another portion of said timing means and said firstswitch means for bypassing said second switch means to condition saidtimer motor for energization in response to said first switch means andsaid another portion of said timing means.

4. In combination with a condensing fabric dryer having means defining arecirculating air stream, means for condensing moisture from saidrecirculating air stream thereby to cool said air stream, means fortumbling fabric in said recirculating air stream, heating means on theupstream side of said tumbling means for heating said recirculating airstream and blower means for initiating said air stream, a controlcircuit comprising timing means for sequentially controlling saidheating means and said blower means in a programmed drying cycle of afirst predetermined duration for delicate fabrics including a timermotor to advance said drying cycle, first switch means thermallyresponsive to the temperature of said recirculating air stream on saidupstream side of said tumbling means and the downstream side of saidcondensing means and in series electrical flow relationship with saidtimer motor for energizing and deenergizing said timer motor, said firstswitch means having a closed position for energizing said timer motorwhen the temperature of said recirculating air stream at said firstswitch means is below a first predetermined value effected by thecooling of the recirculating air stream as it passes through saidcondensing means when the clothes are dry and an open position fordeenergizing said timer motor when the temperature of said recirculatingair stream is above said first predetermined value, second switch meansthermally responsive to the temperature of said recirculating air streamon the downstream side of said tumbling means and the upstream side ofsaid condensing means, said second switch means being electricallyconnected to a portion of said timing means and in selective serieselectrical fiow relationship with said first switch means or saidheating means, said second switch means having a first position inseries with said heating means when the temperature of saidrecirculating air stream at said second switch means is below a secondpredetermined value lower than said first predetermined value to heatsaid recirculating air to dry the clothes and a second position inseries with said first switch means when the temperature of saidrecirculating air stream at said second switch means is above saidsecond predetermined value to condition said timer motor to advance saiddrying cycle, said drying cycle being terminated when said first switchmeans is in said closed position simultaneously with said second switchmeans in said second position to energize said timer motor until saidportion of said timing means deenergizes said control circuit.

5. The combination of claim 4 including means for bypassing said secondswitch means to condition said timing means for sequentially controllingsaid heating means and said blower means in a programmed drying cycle ofa second predetermined duration shorter than said first predeterminedduration for regular fabrics.

6. In combination with a condensing dryer for moist fabric having meansfor agitating said fabric, means defining a recirculating air flowincluding said agitating means, means upstream from said agitating meansfor heating said recirculating air flow, means defining a cooling airflow in heat transfer relationship to said recirculating air flow forcondensing moisture from said recirculating air flow, means foractuating said agitating means and inducing said air flows, and dryingcycle control means having timer switch means for starting andautomatically stopping said heating means and said agitating andinducing means, said control means including a timer motor for operatingsaid timer switch means, a first increasing temperature responsiveswitch means in said recirculating air flow downstream from saidagitating means and in series electrical flow relationship with aportion of said timer switch means, said first switch means having afirst position in series with said heating means and a second position,a second decreasing temperature responsive switch means in saidrecirculating air flow upstream from said agitating means and in serieswith said timer motor and said first switch means in said secondposition, said drying cycle being advanced only when said portion ofsaid timer switch means, said first switch means in said second positionand said second switch means are in electrical supply relationship tosaid timer motor.

7. In combination with a condensing dryer for moist fabric having meansfor agitating said fabric, means defining a recirculating air flowincluding said agitating means, means upstream from said agitating meansfor heating said recirculating air flow, means defining a condenser inheat transfer relationship to said recirculating air flow for condensingmoisture from said recirculating air flow, means for actuating saidagitating means and inducing said air flows, and drying cycle controlmeans having timer switch means for starting and automatically stoppingsaid heating means and said agitating and inducing means, said controlmeans including a timer motor for operating said timer switch means, afirst increasing temperature responsive switch means in saidrecirculating air fiow downstream from said agitating means and upstreamfrom said condenser and in series electrical flow relationship with aportion of said timer switch means, said first switch means having afirst position in series with said heating means and a second position,a second decreasing temperature responsive switch means in saidrecirculating air flow upstream from said agitating means and downstreamfrom said condenser and in series with said timer motor and said firstswitch means in said second position, said drying cycle being advancedonly when said portion of said timer switch means, said first switchmeans in said second position and said second switch means are inelectrical supply relationship to said timer motor.

8. In combination with a condensing dryer for moist fabric having meansfor agitating said fabric, means defining a recirculating air flowincluding said agitating means, means upstream from said agitating meansfor heating said recirculating air flow, means defining a condenser inheat transfer relationship to said recirculating air flow for condensingmoisture from said recirculating air flow, and drying cycle controlmeans having timer switch means for starting and automatically stoppingsaid heating means, said control means including a timer motor foroperating said timer switch means, a first increasing temperatureresponsive switch means in said recirculating air flow downstream fromsaid agitating means and upstream from said condenser and in serieselectrical flow relationship with said timer switch means, said firstswitch means having a first position in series with said heating meansand a second position, a second decreasing temperature responsive switchmeans in said recirculating air flow upstream from said agitating meansand downstream from said condenser and in series with said timer motorand said first switch means in said second position, said drying cyclebeing advanced only when said timer switch means, said first switchmeans, said first switch means in said second position and said secondswitch means are in electrical supply relationship to said timer motor.

9. In combination, casing means defining a fabric drying chamber havingan inlet and an outlet, means connected to said inlet and said outlet toform a closed circuit duct system, means for recirculating air in saidduct system, means adjacent said inlet to said drying chamber forheating said air to a first or second temperature to vaporize moisturefrom said fabric in a drying cycle, means for selecting said first orsecond temperature, means in said duct system for condensing saidmoisture from said recirculating air, power supply means, timer meansfor completing a power circuit to said power supply means and operableby a timer motor to interrupt said power circuit, and means forcontrolling said timer motor to terminate said drying cycle, said lastnamed means including a termination control switch in said recirculatingair at said inlet and in series with said timer motor, said terminationcontrol switch having a closed position when the temperature of said airat said inlet is at a predetermined value higher than either said firstor second temperature, a cycling control switch in said recirculatingair at said outlet and in series with said timer means, said cyclingcontrol switch having a first position in series with said heating meansto dry said fabric when the temperature of said air is below saidpreselected temperature and a second position in series with saidtermination control switch to condition said timer motor for connectionto said power circuit to operate said timer means when said terminationcontrol switch is closed and the temperature of said air is above saidpreselected temperature.

10. The combination of claim 9 wherein said temperature selecting meansincludes means connectable to said power supply means and in series withsaid termination control switch for by-passing said cycling control.

11. In combination, casing means defining a fabric drying chamber havingan inlet and an outlet, means connected to said inlet and said outlet toform a duct system including a condenser, means for recirculating air insaid duct system through said condenser, means adjacent said inlet tosaid drying chamber for heating said air to a first or secondtemperature to vaporize moisture from said fabric in a drying cycle,means for selecting said first or second temperature, power supplymeans, timer means for completing a power circuit to said power supplymeans and operable by a timer motor to interrupt said power circuit, andmeans for controlling said timer motor to terminate said drying cycle,said last named means includ ing a termination control switch in saidrecirculating air on the downstream side of said condenser at said inletand in series with said timer motor, said termination control switchhaving a closed position when the temperature of said air at said inletis at a predetermined value higher than either said first or secondtemperature, a cycling control switch in said air on the upstream sideof said condenser at said outlet and in series with said timer means,said cycling control switch having a first position in series with saidheating means to dry said fabric when the temperature of said air isbelow said preselected temperature and a second position in series withsaid termination control switch to condition said timer motor forconnection to said power circuit to operate said timer 1 1 means whensaid termination control switch is closed and the temperature of saidair is above said preselected temperature.

12. The combination of claim 11 wherein said temperature selecting meansincludes connectable to said power supply means and in series with saidtermination control switch for by-passing said cycling control.

References Cited by the Examiner UNITED STATES PATENTS 2,505,041 4/1950Gorsuch 34-45 Hammell 34-53 Shewmon 3477 Dunkelman 3445 Engel 34-45Hughes 3445 Gray 34-45 WILLIAM F. ODEA, Acting Primary Examiner.

10 NORMAN YUDKOFF, Examiner.

9. IN COMBINATION, CASING MEANS DEFINING A FABRIC DRYING CHAMBER HAVINGAN INLET AND AN OUTLET, MEANS CONNECTED TO SAID INLET AND SAID OUTLET TOFORM A CLOSED CIRCUIT DUCT SYSTEM, MEANS FOR RECIRCULATING AIR IN SAIDDUCT SYSTEM, MEANS ADJACENT SAID INLET TO SAID DRYING CHAMBER FORHEATING SAID AIR TO A FIRST OR SECOND TEMPERATURE TO VAPORIZE MOISTUREFROM SAID FABRIC IN A DRYING CYCLE, MEANS FOR SELECTING SAID FIRST ORSECOND TEMPERATURE, MEANS IN SAID DUCT SYSTEM FOR CONDENSING SAIDMOISTURE FROM SAID RECIRCULATING AIR, POWER SUPPLY MEANS, TIMER MEANSFOR COMPLETING A POWER CIRCUIT TO SAID POWER SUPPLY MEANS AND OPERABLEBY A TIMER MOTOR TO INTERRUPT SAID POWER CIRCUIT, AND MEANS FORCONTROLLING SAID TIMER MOTOR TO TERMINATE SAID DRYING CYCLE, SAID LASTNAMED MEANS INCLUDING A TERMINATION CONTROL SWITCH IN SAID RECIRCULATINGAIR AT SAID INLET AND IN SERIES WITH SAID TIMER MOTOR, SAID TERMINATIONCONTROL SWITCH HAVING A CLOSED POSITION WHEN THE TEMPERATURE OF SAID AIRAT SAID INLET IS AT A PREDETERMINED VALUE HIGHER THAN EITHER SAID FIRSTOR SECOND TEMPERATURE, A CYCLING CONTROL SWITCH IN SAID RECIRCULATINGAIR AT SAID OUTLET AND IN SERIES WITH SAID TIMER MEANS, SAID CYCLINGCONTROL SWITCH HAVING A FIRST POSITION IN SERIES WITH SAID HEATING MEANSTO DRY SAID FABRIC WHEN THE TEMPERATURE OF SAID AIR IS BELOW SAIDPRESELECTED TEMPERATURE AND A SECOND POSITION IN SERIES WITH SAIDTERMINATION CONTROL SWITCH TO CONDITION SAID TIMER MOTOR FOR CONNECTIONTO SAID POWER CIRCUIT TO OPERATE SAID TIMER MEANS WHEN SAID TERMINATIONCONTROL SWITCH IS CLOSED AND THE TEMPERATURE OF SAID AIR IS ABOVE SAIDPRESELECTED TEMPERATURE.